So I heard of somebody on SA making a tree house out of many groups of very large trees. I decided it would be fun to try this out, so I generate a new level.

Not ideal for a big tree. I would have preferred a small, risen island to build my world tree on. But I might as well explore this mountain, since it seems pretty porous and large.

It wasn't long until I realized that those caves were considerably large than I had expected them to be. A closer look revealed crazy stuff.

It's difficult to see there, but the entire mountain is completely hollow inside. It's so big in fact, that the bottom is at sea level, and the top is above the clouds.
I've got several options here, since I really want to do something with this. Shall I make an Ironforge styled fortress, or pop the top off and plant my World Tree, Ghouldrassil, inside this thing?